// include the basic windows header files and the Direct3D header file
#include <windows.h>
#include <windowsx.h>
#include <d3d9.h>
#include <d3dx9.h>

// define the screen resolution and keyboard macros
#define SCREEN_WIDTH 640
#define SCREEN_HEIGHT 480
#define KEY_DOWN(vk_code) ((GetAsyncKeyState(vk_code) & 0x8000) ? 1 : 0)
#define KEY_UP(vk_code) ((GetAsyncKeyState(vk_code) & 0x8000) ? 0 : 1)

// include the Direct3D Library files
#pragma comment (lib, "d3d9.lib")
#pragma comment (lib, "d3dx9.lib")

// global declarations
LPDIRECT3D9 d3d;    // the pointer to our Direct3D interface
LPDIRECT3DDEVICE9 d3ddev;    // the pointer to the device class
LPDIRECT3DVERTEXBUFFER9 t_buffer = NULL;    // the pointer to the vertex buffer
LPDIRECT3DSURFACE9 z_buffer = NULL;    // the pointer to the z-buffer

// mesh declarations
LPD3DXMESH meshSpaceship;    // define the mesh pointer
D3DMATERIAL9* material;    // define the material object
DWORD numMaterials;    // stores the number of materials in the mesh


// function prototypes
void initD3D(HWND hWnd);    // sets up and initializes Direct3D
void render_frame(void);    // renders a single frame
void cleanD3D(void);    // closes Direct3D and releases memory
void init_graphics(void);    // 3D declarations
void init_light(void);    // sets up the light and the material

// the WindowProc function prototype
LRESULT CALLBACK WindowProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam);


// the entry point for any Windows program
int WINAPI WinMain(HINSTANCE hInstance,
                   HINSTANCE hPrevInstance,
                   LPSTR lpCmdLine,
                   int nCmdShow)
{
    HWND hWnd;
    WNDCLASSEX wc;

    ZeroMemory(&wc, sizeof(WNDCLASSEX));

    wc.cbSize = sizeof(WNDCLASSEX);
    wc.style = CS_HREDRAW | CS_VREDRAW;
    wc.lpfnWndProc = (WNDPROC)WindowProc;
    wc.hInstance = hInstance;
    wc.hCursor = LoadCursor(NULL, IDC_ARROW);
    wc.lpszClassName = L"WindowClass1";

    RegisterClassEx(&wc);

    hWnd = CreateWindowEx(NULL,
                          L"WindowClass1",
                          L"Our Direct3D Program",
                          WS_OVERLAPPEDWINDOW,
                          0, 0,
                          SCREEN_WIDTH, SCREEN_HEIGHT,
                          NULL,
                          NULL,
                          hInstance,
                          NULL);

    ShowWindow(hWnd, nCmdShow);

    // set up and initialize Direct3D
    initD3D(hWnd);

    // enter the main loop:

    MSG msg;

    while(TRUE)
    {
        DWORD starting_point = GetTickCount();

        if (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
        {
            if (msg.message == WM_QUIT)
                break;

            TranslateMessage(&msg);
            DispatchMessage(&msg);
        }

        render_frame();

        // check the 'escape' key
        if(KEY_DOWN(VK_ESCAPE))
            PostMessage(hWnd, WM_DESTROY, 0, 0);

        while ((GetTickCount() - starting_point) < 25);
    }

    // clean up DirectX and COM
    cleanD3D();

    return msg.wParam;
}


// this is the main message handler for the program
LRESULT CALLBACK WindowProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch(message)
    {
        case WM_DESTROY:
            {
                PostQuitMessage(0);
                return 0;
            } break;
    }

    return DefWindowProc (hWnd, message, wParam, lParam);
}


// this function initializes and prepares Direct3D for use
void initD3D(HWND hWnd)
{
    d3d = Direct3DCreate9(D3D_SDK_VERSION);

    D3DPRESENT_PARAMETERS d3dpp;

    ZeroMemory(&d3dpp, sizeof(d3dpp));
    d3dpp.Windowed = TRUE;
    d3dpp.SwapEffect = D3DSWAPEFFECT_DISCARD;
    d3dpp.hDeviceWindow = hWnd;
    d3dpp.BackBufferFormat = D3DFMT_X8R8G8B8;
    d3dpp.BackBufferWidth = SCREEN_WIDTH;
    d3dpp.BackBufferHeight = SCREEN_HEIGHT;
    d3dpp.EnableAutoDepthStencil = TRUE;    // automatically run the z-buffer for us
    d3dpp.AutoDepthStencilFormat = D3DFMT_D16;    // 16-bit pixel format for the z-buffer

    // create a device class using this information and the info from the d3dpp stuct
    d3d->CreateDevice(D3DADAPTER_DEFAULT,
                      D3DDEVTYPE_HAL,
                      hWnd,
                      D3DCREATE_SOFTWARE_VERTEXPROCESSING,
                      &d3dpp,
                      &d3ddev);

    init_graphics();    // call the function to initialize the triangle
    init_light();    // call the function to initialize the light and material

    d3ddev->SetRenderState(D3DRS_LIGHTING, TRUE);    // turn on the 3D lighting
    d3ddev->SetRenderState(D3DRS_ZENABLE, TRUE);    // turn on the z-buffer
    d3ddev->SetRenderState(D3DRS_AMBIENT, D3DCOLOR_XRGB(50, 50, 50));    // ambient light

    return;
}


// this is the function used to render a single frame
void render_frame(void)
{
    d3ddev->Clear(0, NULL, D3DCLEAR_TARGET, D3DCOLOR_XRGB(0, 0, 0), 1.0f, 0);
    d3ddev->Clear(0, NULL, D3DCLEAR_ZBUFFER, D3DCOLOR_XRGB(0, 0, 0), 1.0f, 0);

    d3ddev->BeginScene();

    // SET UP THE TRANSFORMS

    D3DXMATRIX matView;    // the view transform matrix
    D3DXMatrixLookAtLH(&matView,
    &D3DXVECTOR3 (0.0f, 4.0f, 8.0f),    // the camera position
    &D3DXVECTOR3 (0.0f, 0.0f, 0.0f),    // the look-at position
    &D3DXVECTOR3 (0.0f, 1.0f, 0.0f));    // the up direction
    d3ddev->SetTransform(D3DTS_VIEW, &matView);    // set the view transform to matView 

    D3DXMATRIX matProjection;    // the projection transform matrix
    D3DXMatrixPerspectiveFovLH(&matProjection,
                               D3DXToRadian(45),    // the horizontal field of view
                               SCREEN_WIDTH / SCREEN_HEIGHT,    // the aspect ratio
                               1.0f,    // the near view-plane
                               100.0f);    // the far view-plane
    d3ddev->SetTransform(D3DTS_PROJECTION, &matProjection);    // set the projection

    static float index = 0.0f; index+=0.03f;    // an ever-increasing float value
    D3DXMATRIX matRotateY;    // a matrix to store the rotation for each triangle
    D3DXMatrixRotationY(&matRotateY, index);    // the rotation matrix
    d3ddev->SetTransform(D3DTS_WORLD, &(matRotateY));    // set the world transform


    // draw the spaceship
    for(DWORD i = 0; i < numMaterials; i++)    // loop through each subset
    {
        d3ddev->SetMaterial(&material);    // set the material for the subset
        meshSpaceship->DrawSubset(i);    // draw the subset
    }

    d3ddev->EndScene(); 

    d3ddev->Present(NULL, NULL, NULL, NULL);

    return;
}


// this is the function that cleans up Direct3D and COM
void cleanD3D(void)
{
    meshSpaceship->Release();    // close and release the spaceship mesh
    d3ddev->Release();    // close and release the 3D device
    d3d->Release();    // close and release Direct3D

    return;
}


// this is the function that puts the 3D models into video RAM
void init_graphics(void)
{
    LPD3DXBUFFER bufShipMaterial;

    D3DXLoadMeshFromX(L"spaceship 2.x",    // load this file
                      D3DXMESH_SYSTEMMEM,    // load the mesh into system memory
                      d3ddev,    // the Direct3D Device
                      NULL,    // we aren't using adjacency
                      &bufShipMaterial,    // put the materials here
                      NULL,    // we aren't using effect instances
                      &numMaterials,    // the number of materials in this model
                      &meshSpaceship);    // put the mesh here

    // retrieve the pointer to the buffer containing the material information
    D3DXMATERIAL* tempMaterials = (D3DXMATERIAL*)bufShipMaterial->GetBufferPointer();

    // create a new material buffer for each material in the mesh
    material = new D3DMATERIAL9[numMaterials];

    for(DWORD i = 0; i < numMaterials; i++)    // for each material...
    {
        material = tempMaterials.MatD3D;    // get the material info
        material.Ambient = material.Diffuse;    // make ambient the same as diffuse
    }

    return;
}


// this is the function that sets up the lights and materials
void init_light(void)
{
    D3DLIGHT9 light;    // create the light struct

    ZeroMemory(&light, sizeof(light));    // clear out the struct for use
    light.Type = D3DLIGHT_DIRECTIONAL;    // make the light type 'directional light'
    light.Diffuse.r = 0.5f;    // .5 red
    light.Diffuse.g = 0.5f;    // .5 green
    light.Diffuse.b = 0.5f;    // .5 blue
    light.Diffuse.a = 1.0f;    // full alpha (we'll get to that soon)

    D3DVECTOR vecDirection = {-1.0f, -0.3f, -1.0f};    // the direction of the light
    light.Direction = vecDirection;    // set the direction

    d3ddev->SetLight(0, &light);    // send the light struct properties to light #0
    d3ddev->LightEnable(0, TRUE);    // turn on light #0

    return;
}